The ever-widening gap between rich and poor has meant that the real, low-income, middle classes are

Somehow, an ideological assault on the welfare state is being dressed up as an attempt to make things fairer and more equal - cuts in benefits to enable social mobility, no less. It was Nick Clegg's turn to make a fraudulent case this past week. Life chances, the Deputy Prime Minister suggested, are determined not by poverty, but by parenting. "We must not remain silent on what is an enormously important issue. Parents hold the fortunes of the children they bring into this world in their hands."

It's a grossly naive statement, which Clegg used to attack the welfare state: the lack of social mobility under Labour proved, he said, that Labour's redistribution towards the poor was ineffectual (it proves nothing of the sort) and had "no discernible impact" on the opportunities of the next generation. Hence, it is parents who must make the difference.

“I know, like any mother or father, how difficult it can be to find the time and the energy to help, for example, with your children's homework at the end of a busy day," claimed the Deputy Prime Minister. No, Nick, you do not know how difficult it can be to find the energy for homework when you are raising children alone on a low income, juggling work and after-school care. The claim was as disingenuous or downright stupid as David Cameron's claim to be middle class like the rest of us.

Social mobility

If you really wanted to increase social mobility in Britain, you would be better off addressing the very rich than attacking the very poor. I've been reading a fascinating report about the real middle classes in Britain - not the pretend political ones or the journalists who come up with headlines describing tax rises on incomes above £150,000 as "middle-class tax hikes".

Where I live, in the south beyond London, real middle-class families are real middle-class families: they live on perhaps between £25,000 and £40,000 a year, rarely eat out, have the heating on only five months a year, for a few hours a day (the price of oil makes heating a huge expense in the countryside), go on a foreign holiday perhaps once every five years, and survive on a combination of low- to middle-income jobs and tax credits.

After-school clubs are a worrying pecuniary strain, not a competition for who can stuff the most extras into a five-day week. If the car breaks down, it can be a financial disaster, not just an inconvenience. Mortgage payments are precarious. These are the middle classes who are now dipping into savings accounts to make ends meet, the same ones that a YouGov and Markit survey this month found were increasingly worried about the higher costs of living.

My new favourite academic, Danny Dorling at Sheffield University, has done a stunning piece of work about these middle classes (Poverty and Wealth Across Britain, 1968-2005, Joseph Rowntree Foundation). Well, it wasn't really about them, but it's interesting about them in passing. Best known for his work exposing the geographical polarisation of Britain into rich and poor, south and north, Dorling came up with a startling theory about the middle classes: they are rapidly shrinking.

The proportion of Britons classified by Dorling and his fellow researchers as neither poor nor wealthy - in other words, middle class - fell from two-thirds in 1980 to half in 2000. The researchers' definition of "wealthy" was modest: if you held housing equity worth between 30 and 40 per cent of the inheritance-tax threshold at any given time, you were classified as asset-wealthy. Being "neither poor nor wealthy" meant you were not breadline-poor - not renting or ill, not lacking a car or central heating or a job - but nor were you asset-wealthy. That is, you did not hold housing wealth of £19,020 in 1983, or £76,692 in 1999. You were middle-middle class.

By 2000, the proportions who were breadline-poor and asset-wealthy had increased, but those in the middle had shrunk from 66 to 50 per cent. And they had shrunk the furthest in London and southern England - what Dorling called "the gradual disappearance of the non-poor, non-wealthy 'middle' households from London and the south-east". The polarisation of wealth pushed them out: "Over time it has become clear that there is less room in the south for them; they have either moved away, or become wealthy or poor." There have been many more indications since that the polarisation of rich and poor in Britain is increasing.

This explains the apparent conundrum over public attitudes to inequality. Three-quarters of respondents to surveys consistently say they consider the gap between rich and poor to be too wide, but far fewer of them actually support the redistribution of income from the better-off to the less-well-off. That is because the vulnerable middle classes think it means redistribution of their income to the poorest, and that worries them.

Uphill struggle

As a consequence of the growing polarisation between rich and poor in Britain, the new middle classes that drove the rise of Thatcherism and New Labour are shrinking, and those that are left in the middle are feeling increasingly insecure. The National Equality Panel reported this year that evidence suggests intergenerational (upward) mobility is higher in countries that are more equal.

If upward social mobility is harder in unequal societies, downward is an easy trip. To quote Dorling again: "Those living at the top of the hill will live far more stress-free lives if they are worrying less about dropping down the slopes."

If I were a politician whose party draws support largely from southern England, and if I were going to talk about social mobility, I would stop lecturing the poor and pay quite a lot of attention instead to the nervous middle classes living halfway down that hill.